1. Field of the Invention
The present invention relates generally to cargo lifting apparatus and methods, and more particularly to a multipurpose cargo cage and a spreader attachment for carrying out various cargo transportation operations without the necessity of rerigging the apparatus.
2. Description of the Prior Art
It is common among the shipping industry to load into the hold of a ship various goods produced at a first location and transport the goods to a remote location. An example of such goods frequently shipped via this mode is citrus. Citrus is traditionally transported by first packaging the citrus into crates or boxes, and then loading a quantity of crates onto pallets adapted to be picked up and moved by fork lifts. As can be appreciated, the use of fork lifts and pallets increase the production and economy of moving the goods from one location to another.
Cargo ships used to transport citrus typically include multiple decks for storing the pallets loaded with crates. As the lower decks are filled with pallets, the maneuverability within the ship's hold is gradually reduced until, as the last few pallets are loaded in the top deck, there is no longer any room to permit machinery such as a fork lift to operate. To solve this problem, the final pallets to be placed in the hold are configured with belts or cables (i.e., preslung) that permit the pallets to be dropped into the hold directly with an overhead crane. When unloading the ship, a crane is first used to remove the last-loaded pallets using the belts or cables. To lift the preslung pallets, the crane is fitted with a rigging including a spreader attachment adapted to lift the preslung pallets. The crane raises the initial pallets until they clear the ship's deck, and then the crane swings laterally stopping above a dockside platform where the pallets are lowered for unloading or reloaded for ground transportation.
Once the initial pallets immediately under the hatchway are removed creating a cleared area on the top deck, the crane may lower the first spreader to the dock to be disconnected and a second spreader with different rigging is adapted to lower heavy machinery such as a fork lift picked up to transfer the machinery to the ship's hold. This rerigging of the crane is necessary to place the fork lift in the ship's hold, but comes at a cost of time and manpower. Once the fork lift is located in the hold, the second spreader is removed from the crane and a third spreader is placed on the crane. This third spreader is adapted to lift large cargo cages loaded with crates or cartons of citrus and the like. The cargo cages are lifted and swung to the dockside platform until the entire cargo has been unloaded from the ship's hold. Finally, the third rigging must be replaced again with the second rigging so that the heavy equipment can be removed from the ship's hold. The unloading operation just described requires a minimum of four rigging changes to effect the loading and unloading operations. Each time the crane must be fitted with a new rigging, time is wasted and manpower is spent waiting for the spreader exchange to be effected.
There are many types of spreaders, slings, and lifting devices in the prior art for lifting a pallet or a cargo cage. U.S. Pat. No. 5,163,726 to Boos et al. discloses a spreader bar and overheight attachment with an automatic latching mechanism. Koide et al., U.S. Pat. No. 5,232,257, discloses an automatic hooking apparatus and ship cargo gear using the same. U.S. Pat. No. 5,052,734 to Hasegawa et al. discloses a cargo container lifting spreader compensating mechanism for facilitating engagement by the spreader with cargo containers having out-of-plane twistlock engagement receptacles with rotatable connectors. Perez et al., U.S. Pat. No. 4,736,975 is directed to an apparatus and method for loading and unloading pallets with a sling. Schweikert, U.S. Pat. No. 4,550,940, discloses a pallet-bar lift and support apparatus. U.S. Pat. No. 4,358,145 to Svensson discloses a lifting device for a container with reciprocating coupling mechanisms. U.S. Pat. No. 4,068,878 to Wilner discloses a twist lock coupling for use in handling cargo containers of the type used in I.S.O. systems. While the aforementioned systems and apparatus are directed to various attempts to reliably lift cargo, the art lacks a device and system for achieving the objectives and goals of the present invention.